1. Field of the Invention
The present invention relates to an organic electroluminescent element used preferably for various kinds of displays, light emitting elements, or the like, and a photocatalyst containing coating solution for an organic electroluminescent element used for the production thereof.
2. Description of the Related Art
Conventionally, in the method for manufacturing an organic electroluminescent (hereinafter it is also referred to as “organic EL”) element, an organic EL layer, an electrode layer, or the like have been formed by such as the photolithography method, the mask deposition method. However, the photolithography method involves a problem of the process complication and the high cost, while as the mask deposition method, requiring an expensive vacuum device, is problematic in terms of the yield and the cost.
Recently, a method of using a photocatalyst has been proposed as a method for patterning the organic EL layer and the electrode layer (see Japanese Patent Application Laid-Open (JP-A) No. 2000-223270). Specifically, by forming a photocatalyst containing layer to have the surface characteristic change by the action of the photocatalyst accompanied by the energy irradiation, and directing an energy in a pattern to the photocatalyst containing layer surface, patterns with different characteristics are formed on the photocatalyst containing layer surface. Thereafter, utilizing the characteristic difference of the characteristic changeable patterns formed on the photocatalyst containing layer, the organic EL layer, the electrode layer, or the like are patterned. According to the method, the organic EL layer, the electrode layer, or the like can be formed highly precisely, utilizing the above-mentioned characteristic difference so that the labor needed for patterning can be dramatically saved. However, in the case the activation of the above-mentioned photocatalyst is low, the pattern formation of the characteristic changeable takes time so as to cause the energy spreading around or the like. As a result, the pattern to be formed is made thick to cause a problem that the organic EL layer, the electrode layer, or the like can hardly be formed highly precisely. Furthermore, depending on the kind of the above-mentioned photocatalyst containing layer, the light emission characteristic of the organic EL element is lowered, and thus it is problematic.